Selector switch brush



April 1952 G. DEAKIN 2,591,683

SELECTOR SWITCH BRUSH Filed June 25, 1948 FIG. I.

INVENTQR GERALD DEAKIN ATTORNEY Patented Apr. 8, 1952 UNITED STATES PATENT OFFICE SELECTOR SWITCH BRUSH Gerald Deakin, New York, N. Y., assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application June 25, 19 18, Serial No. 35,201

14 Claims. 1

This invention relates to new and useful improvements in brushes arranged to wipe over terminals of selector switches, and more particularly to arrangements for centering such brushes on the terminals.

In my prior application Serial No. 547,126 filed July 29, 1944, now Patent Number 2,495,701, issued January 31, 1950, I disclosed a wiper structure in which positioning of the wipers was insured by means of guides of insulating material on either side of the wiper and each engaging two 01' more terminals. While such arrangement satisfied the requirement of properly aligning the wipers with respect to the terminals, particles of insulating material became transferred from the guides to the terminals, impairing the satisfactory operation of the device.

This drawback is avoided in accordance with the present invention, by positioning metal guides on either side of the wipers. These guides are mounted on the spacer of insulating material carrying the wiper, said guides being in the form of wipers engaging the terminals at points above the line of engagement of the terminals by the wiper proper. The guides are spaced from the wiper so that when a wiper contacts a terminal the guides do not, and vice versa. On account of this spacing between the wiper and guides,-

the contact pressure which the wiper exerts on a terminal while at rest thereon cannot be varied by the guides and thus disturbances such as noise during conversation are eliminated.

With this object in view I provide the construction which will be clear from the following description, claims and drawings, in which:

Fig. 1 is a plan view of a brush unit; and

Fig. 2 is a section along the lines 22 of Fig. 1.

A brush unit consists of a brush mounting frame or spacer I of fiber or other suitable insulating material having a central opening 2, and two lateral mounting prongs or trunnions 3, 4 by means of which spacer I may be mounted in a brush carriage, not here shown but fully described in my copending application No. 697,148, filed September 14, 1946, which was issued as Patent No. 2,565,480 on August 28, 1951.

The spacer supports a brush wiper consisting of two distinct complementary segments 5 and 5 of suitably tempered spring material, e. g. Phosphor bronze. The parts of the under side of the assembly are indicated in Figure 2 with primed reference numerals agreeing with the ref erence numerals of the corresponding parts of the upper side. As shown in the last mentioned prior application, when mounted in a brush carriage each segment has a first restricted contact tip I which engages a feeder strip 8 and a second restricted contact tip 9 for successively engaging evenly spaced terminal pins I0 projecting from a terminal bank II of a selector. Feeder strip 8 passes between the first tips I and terminal pins it) pass between the second tips 9 of the wiper.

Each complementary segment 5, 6 comprises triangular sections I2 and I3 which lie between the contacting tips and centrally depressed areas or waists I4, I5 of the segments. Waists I4, I5 contact one another and extend laterally to form tabs or wings I6, I! on one segment in juxtaposed relationship to corresponding wings on the complementary segment.

The complementary brush segments are secured to one another by means of metal bars I8, I9 which contact waist portions I4, I5 in opening 2 and are fastened to one another by rivets 20, 2I passing through wings I6, I1. End portions 22, 23 of each of the bars are pressed against the opposite longitudinal ends of spacer I surrounding opening 2. Segments 5 and 6 are, therefore, accurately positioned with respect to one another and to spacer I by means of bars I8, I9.

As shown at 24 the edge portions of each complementary brush segment are upturned thereby giving added stiffness to the segments and pre venting warping or decrease of pressure exerted by the segments at their contacting tips.

In order to insure proper guidance of the brush unit as it travels back and forth over terminal pins Ill, pairs of metal guide members 25, 26 are fastened by rivets 21, 28 to either side of the spacer I adjacent the sides of triangular portion I3 and complementary portion I3. The guide members do not project as far from the side of spacer I as the wiper and engage the terminals above points of engagement by tip 9.

Each guide member consists of a metal plate having a restricted contact making portion, such as 29, 38 shown for plates 25, 26. These contact making portions of the guide plate engage pins II! in a manner similar to the contact making portions of the brush segments except that, as above stated, the plates contact the pins near their upper ends or tips and the wiper farther down. The spacing between the contact points 29, Bil of the plates 25, 26 and the wiper tip 9 is such that when tip 9 of the wiper is centered on a terminal pin III, contact making portions 29, 3% of the guide plates do not make contact with any pins 1B, and when contact making portions 29, 30 of the guide plates contact pins I 0, contact tip 9 of the wiper does not contact a pin.

Thus the guide plates perform their function of guiding and supporting the brush unit only during those periods of time when it is necessary, i. e. when the wiper is not centered on a terminal. When the wiper is centered on the selected terminal pin 10, then the guides. are out of engagement with the terminal pins whereby the contact between the terminal pin and the wiper is determined solely by the resiliency of the latter and cannot be disturbed by one of the guides which through the spacer might tend to move the wiper with respect to the terminal pin. As far as this phase of the invention is concerned, it might successfully be employed in connection with other wiper constructions also, the sole requirement being that the guide or guides 'must be so spaced from the wiper that they engage the terminal pins when the wiper is out of engagement therewith and vice versa.

What is claimed is:

1. In a brush unit for selector switches having feeder strips and terminal pins, a spacer of insulating material, a brush wiper on each side of said spacer and fastened thereto, each wiper having a first and a second contact making end formed to engage a feeder strip and the terminal pins respectively, and metal guiding means fastened to the spacer and electrically insulated from said brush wipers, said metal guiding means projecting into cooperative relationship with the terminal pins.

2. The brush unit according to claim 1, and in which the guiding means comprise metal plates fastened to each side of the spacer adjacent the second ends of the wipers, each plate having a contact making portion cooperating with the pins, the contact making portions of the wipers and plates engaging different portions of the pins.

3. The brush unit according to claim 2, and in which the contact making portions of the plates engage the pins near their tips and those of the wipers below the tips.

4. The brush unit according to claim 1, and in which the guiding means are provided, one on either side of a wiper.

5. The brush unit according to claim 1, and in which the terminal pins are uniformly spaced and the spacing between a pin contacting portion of the wiper and the contact making portions of the guiding means is greater than the spacing between adjacent pins but less than double said space.

6. The brush unit according to claim '1, and in which the guiding means engage terminal pins when the second contact making ends of the wipers are between two adjacent terminal pins.

'7. The brush unit according to claim 1, and mounting trunnions projecting-from the spacer.

8. In a brush unit for selector switches having spaced terminal pins, a wiper arranged successively to wipe over the pins, an insulating mounting frame for the wiper, and a metal guide means for said wiper fastened to the frame and engaging the pins only when the wiper does not, and vice versa.

9. The brush unit according to claim 8, and in which the guide comprises two plates having ends formed to grip the pins.

10. The brush unit according to claim 8, and in which two guides are provided, one on either side of the wiper, one guide engaging the pins ahead and the other after the wiper.

11. The brush unit according to claim 10, and in which the wiper comprises two resilient sections having ends formed to grip the pins, and each guide comprises two plates having ends formed to grip the pins.

12. In a brush unit for selector switches having feeder strips and terminal pins, a spacer of insulating material having a central opening, a brush wiper on each side of said spacer, each wiper having a first and a second contact making end projecting from the spacer and formed to engage a feeder strip and the terminal pins respectively, each wiper further having a central portion within the opening in the spacer and a metal bar contacting with and fastened to the central portion of each wiper within the opening in said spacer and having end portions projecting beyond the opening and'overlying the spacer at opposing ends of the central opening within said insulatin spacer.

13. The brush unit according to claim 12, and trunnions for mounting the spacer integral with and projecting from the spacer.

14. In a brush unit for selector switches having feeder strips and terminal pins, a spacer of insulating material having a central opening, mounting trunnions integral with and laterally projecting from the side edges of the spacer, a brush wiper on each side of said spacer, each wiper having a first and a second restricted contact making end projecting beyond the upper and the lower edges of the spacer and formed to engage a feeder strip and the terminal pins, respectively, each wiper further having a waist portion contacting within the opening of the spacer the corresponding portion of the other wiper, lateral wings projecting from each waist portion within said opening, triangular sections joining the ends of each wiper with the waist portion, the triangular sections and the ends having upturned stiffening edges, a metal guide fastened to each side of the spacer at its lower edge on each side of but spaced from the wiper and projecting into cooperative relationship with the terminal pins wiping over them nearer their tips than the second contact making end of the wiper, a metal bar contacting the waist portion of each wiper within the opening in the spacer and having ends projecting beyond the opening and overlying the spacer, and rivets fastening the metal bars to the waist portions of the wipers and the wings thereof whereby the overlying ends of said metal bars clampingly engage said spacer.

GERALD DEAKIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,880,775 Butler et al Oct. 4, 1932 2,343,100 Van Inwagen Feb. 29, 1944 2,347,727 Barber May 2, 1944 2,457,589 Miller Dec. 28, 1948 FOREIGN PATENTS Number Country Date 558316 Great Britain Dec. 24, 1942 

